Use OstroVit Creatine Monohydrate Orange according to the suggested amount on the product label, and avoid increasing the serving just because you train harder on a given day. With creatine, regular use is the key point: it works through gradual muscle saturation, so the exact time of day is usually less important than taking it consistently.
You can fit it around your routine in the way you are most likely to remember. Some people prefer it near training, while others take it with a meal or at the same time each day. On rest days, it can still be used as part of the same routine if that matches the label directions and your personal regimen.
For mixing, add the powder to water or juice and stir or shake well. The orange flavour is useful if you dislike the plain taste or texture of unflavoured creatine. If any powder settles at the bottom, add a little more liquid and swirl again rather than assuming the serving was ineffective.
Drink enough fluids throughout the day, especially if your training is intense or you sweat a lot. If you are pregnant, breastfeeding, have kidney-related concerns, use medication or combine several specialist sports supplements, ask a qualified professional before using it.